1. Field of the Invention
The present invention relates to an endoscope system including an endoscope that has an elongated insertion unit.
2. Description of the Related Art
In general, endoscopes adaptable to industrial use or medical use have an elongated insertion unit that is inserted into a lumen. The insertion unit of this type of endoscope has a bending section formed adjacently to a distal section thereof. By bending the bending section, the endoscope can be angled in any observational direction.
For example, there is the work of inserting the elongated insertion unit of an endoscope for industrial use into the deep end of a tortuous pipe that has a plurality of elbows. During the work, the insertion unit is passed the elbows by adroitly handing the insertion unit, for example, thrusting it, angling it, or twisting it. Consequently, the distal section of the insertion unit reaches a target region, and the target region can be observed.
In the inserting work, if there is a large difference between the inner diameter of a pipe and the outer diameter of the insertion unit, when the insertion unit is thrust, the flexible tube of the insertion unit may warp largely. This makes it hard to adroitly insert the insertion unit into the target region. On the other hand, a user needs expertise until he/she masters the technique of passing several elbows of a pipe, of which inner diameter is slightly larger than the outer diameter of the insertion unit, by adroitly handling the insertion unit.
Consequently, when considered solely workability for insertion, it is preferred to procure an endoscope having an insertion unit whose outer diameter is optimal relative to the inner diameter of a tube.